Ramularia risk on the rise

Diagnostic tests have shown barley spotting disease ramularia can be present on seed, and opens up the possibility its spread could be due to seed-borne infections as well as air-borne spores, according to SAC plant pathologist Simon Oxley.

The discovery was made when a new specific ramularia diagnostic test was used on over 50 seed stocks from the past two seasons, he said.

“We found ramularia on 100% of one year’s stocks.”

Seeds from the stocks grown on in the glasshouse confirmed ramularia was present on the developing plants, he said.

Finding the seed-borne route for the disease was a surprise.

“Previously we’d always thought it was blown into the crop.

Now it looks like it could work up inside the plant.

It could also be a reason why we’re spreading problems from one area to another.”

The next step was to discover whether the infection was on the seed coat or deep-seated.

“If we can find out where it is in the seed, we might be able to use seed dressings to knock it out.”

SAC research was also attempting to develop a forecasting system for the disease by finding out which factors were most important in its development.

The project had two years’ data so far.

“Depending on what factors are important we might need to collect the data internally and then put a warning out through text message.”

The intention was to start putting a trial model together this winter ready for trial testing next season.

“I suspect it will be three to four years before it is ready commercially,” Dr Oxley said.

Longer term the aim must be to develop varietal resistance.

“Varieties, such as Decanter, appear to get less ramularia than others, which is a good clue for SCRI to work with.

We need to find out which genes are effective, and if we can isolate them to breed into new varieties.”